There are two intertwined goals of this research: 1) to elucidate the behavioral role of the amygdala in the cat by studying the activity of single units in the freely moving animal; 2) to develop a viable experimental approach to the problem of the neuronal bases of mammalian behavior which will be generalizable to structures such as those in the limbic system, basal ganglia, diencephalon, and association cortex. The first of these goals will be accomplished by studying the activity of each of a large number of amygdala neurons in a sequence of experimental paradigms by means of chronically implanted flexible microelectrodes. The paradigms were chosen largely on the basis of their presumed relevance to amygdala function. The general headings under which one or several amygdala unit experiments will be conducted are as follows: a. Sleep-Wakefulness; b. Sensory Stimulation; c. Electrophysiological Studies of Input-Output Relations; d. Functional Role of Serotonin; e. Cross-Correlations with units on Other Structures; f. Behavioral Inhibition.